Heat olive oil in a large skillet over medium-high heat and brown sausage links for 6β7 minutes, turning occasionally until cooked through, then slice and set aside.
Add diced onion and sliced zucchini to the skillet and cook 5β6 minutes until just tender, stirring occasionally.
Pour marinara sauce into the skillet with the vegetables, return sausage, and simmer for 2 minutes.
Tear fresh mozzarella over the top and cover the skillet for 1 minute to allow cheese to soften, then garnish with fresh basil before serving.
Photo: Nick Nice / Unsplash